$ git clone -n https://github.com/xcp-ng-rpms/xapi.git /var/lib/mock/v8.3-u-gtn1-10009-28659/root/chroot_tmpdir/scmroot/xapi
Cloning into '/var/lib/mock/v8.3-u-gtn1-10009-28659/root/chroot_tmpdir/scmroot/xapi'...
$ git fetch origin a9f8cb734b61e148293c6f8968bf738d40fed455:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xapi
 * [new ref]         a9f8cb734b61e148293c6f8968bf738d40fed455 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a9f8cb7 bump release for test build